This invention relates to luer access devices for the engagement of conventional luer lock connectors and particularly to systems using penetration of a luer tip of a luer lock connector into a septum to achieve access for medical fluid transfer.
The high cost of the nascent "needle free" medical fluid access systems is well known. Much of this cost is related to the widespread use of cannulae for penetration of septa or to the use of expensive luer activation valves and internal spike based systems.
The ideal medical fluid access device must be applicable to all medical fluid delivery or blood access systems including IV lines, saline wells, arterial lines, hemodialysis lines, and any other site wherein fluid access for blood withdrawal or drug and fluid injection is desired and must have the following nine important characteristics:
1. Backward compatibility with conventional blunt cannulae. PA1 2. Absence of flow limitation below the rate of flow through the luer cannula. PA1 3. Absence of substantive negative pressure upon withdrawal of the luer lock connector from the device. PA1 4. Low force of insertion of the luer tip into the device. PA1 5. Absence of substantive kickback after luer tip slip insertion so that a luer tip will remain in a resting advanced position after insertion. PA1 6. Small footprint and low profile (as is associated with conventional simple reseals). PA1 7. Isolation of fluid flow to the central flow path within the device. PA1 8. The basic design must provide a configuration which can be deployed without fluid dead-space in connection with the fluid interface. (Dead-space, such as that associated with the fixed lumen of central spike, will leave residual blood in the device if it is used for blood withdrawal). PA1 9. Manufacturing cost similar to conventional standard reseals. (These simple devices were the basic access sites for fluid access for over 2 decades and constitute the cost basis for the optimal target manufacturing cost of any new system which aspires to become the new universal standard.)
It is an object of the present invention to provide a medical fluid access device, which can provide all of these nine characteristics and which can become the new universal standard for medical fluid access.
U.S. Pat. No. 5,466,219 (the disclosure of which is incorporated by reference as if completely disclosed herein) provides background for the present invention and discloses a septum with a central slit having a low penetration resistance adjacent an upper septum portion and tight sealing adjacent a lower septum portion. This type of septum design allows penetration by a large diameter cannula, such as a luer tip, to be achieved with an acceptable penetration force at the atmospheric interface while providing tight sealing in a lower portion of the septum. U.S. Pat. No. 5,474,544 (the disclosure of which is incorporated by reference as if completely disclosed herein) also provides background for the present invention and discloses a luer penetration receiving septum which eliminates the need for cannulae and needles. This invention discloses an elongated solid septum with a central slit. The septum includes a solid centrally slitted portion projecting centrally within the housing. This portion has a reduced transverse dimension lateral to the long transverse axis of the slit which effectively reduces the lateral deflection diameter of the septum after a luer tip has been received into a central slit so that the septum and housing and the penetrating luer taper can be contained within the confines of a cylindrical luer lock connector. The preferred embodiment includes slots in alignment with the long transverse axis of the slit to receive a portion of the laterally displaced septum volume on penetration by the luer tip. The use of properly positioned slots allows the lower portion of the septum to have sufficient mass lateral to the slit to reliably rebound to its resting shape thereby rapidly closing the slit when the luer tapered cannula has been withdrawn.
Referring to FIG. 18, there is schematically shown therein a structure 2010 that corresponds to a mock-up prop device that was made for showing the concept of the invention of the '544 patent. That device was formed by drilling out lateral portions of the septum 2034 to define cavities 2068 for receiving displaced septum portion(s) resulting from insertion of a male luer into the septum 2034. More particularly, to form a luer receiver having a septum with an extension of reduced width, a commercially available injection site for receiving a narrow blunt cannula was drilled out from each side with a thin circular grinding wheel oriented in parallel to the slit and coming in through the housing 2012, perpendicular to the slit to form cavities 2068 for receiving displaced septum portions when a male luer is inserted into the septum 2034. It is evident that to ensure a patent fluid passage to the patient, in a commercial form the septum would be preformed to have the desired extension and the housing walls would not be drilled through, e.g. the cavities 2068 would be defined entirely by the reduced thickness of the septum extension 2040, or cutouts in the housing wall would not extend entirely therethrough. In this structure, the septum 2034 was fully received within the housing 2012 and cavities 2068 are defined lateral to the septum extension 2040.
The present invention includes an improved septum and housing configuration which is inexpensive to manufacture and which provides features increasing the rebound to the resting "closed slit" position thereby reducing the potential for leakage when used in situations of high pressure, such as arterial lines or hemodialysis lines. The present invention also provides a configuration which is associated with a reduced penetration force requirement for penetration of the septum, even with a flat faced large diameter luer tip, and which reduces or eliminates the negative pressure associated with luer tip withdrawal.
Generally the luer penetration receiver comprises a housing having an inlet and an outlet. The housing includes a proximal portion sized to be received and threaded into the conventional cylindrical luer lock end. An elongated elastomeric septum defining a longitudinal axis is provided having a sealing portion within the housing. The septum includes a target portion comprising an upper septum portion and a lower septum portion. The upper portion preferably projects above the housing and defines an atmospheric face. The lower portion is positioned adjacent the housing inlet. A slit extends through the septum from the sealing portion to the atmospheric face. The slit defines a longitudinal axis along the longitudinal axis of the septum and a long transverse axis along the transverse axis of the septum. The septum can include opposing lateral slits or grooves which separate the upper portion from the lower portion. The septum can further include an extension which projects centrally within the housing and has a reduced transverse width perpendicular to the long transverse axis of the slit when compared to the upper portion.
The septum preferably occludes the housing inlet. The upper portion of the septum preferably has a cross-sectional area greater than the cross-sectional area of the luer tip. The inlet is configured to provide opposing inlet wall platforms positioned below the upper septum portion. (The platforms can also extend around the septum to be circumferential). The septum upper portion preferably rests on the upper surface of the inlet wall platforms. At least a portion of the opposing platforms are positioned below opposing lateral portions of the upper portion of the septum lateral to and in relative alignment with the long transverse axis of the slit. The platforms preferably include opposing projections, which project into the opposing slits in the lateral wall of the septum. The opposing projections within the opposing slits preferably have upwardly sloping surfaces and the surface is highest adjacent the lateral edge of the septum to lever the opposing portions of the lateral septum portions upwardly with the leverage force being directed toward and along the long transverse axis of the slit thereby providing rapid resealing of the slit upon withdrawal of the luer tip from the slit. In association with the wedge effect of the sloping surfaces below the upper septum portion, the advancement of the tip against the central portion of the septum face induces relative upward deflection of the lateral portions of the septum by tipping the lateral walls upward as the central portion of the face deflects downward. In the preferred embodiment, the inlet wall platform is circumferential and extends from a low position of opposing wall troughs adjacent and perpendicular to the ends of the central slit, to a high position defining opposing wall peaks extending along an axis in relative alignment with the long transverse axis of the slit. This septum and inlet configuration facilitates penetration by the large diameter luer tip by allowing modest central downward deflection while tipping opposing lateral portions of the face upward thereby inducing a "facial valley" with laterally opposing upwardly sloping septum portions of the face aligned with the central slit . This induced configuration focuses the insertion force to wedge open the slit in opposing vectors perpendicular to the slit. Further, the upward deflection of the opposing lateral portions of the septum effectively reduces the lateral cross-sectional area of the upper septum portion at the atmospheric face thereby facilitating capture of the septum by the surrounding luer lock housing during penetration. Upon withdrawal of the luer tip, the leverage force discussed supra causes the slit at the atmospheric face to be forcibly closed. An important and unexpected benefit of using focused levered upward lateral deflection to seal the uppermost portion of the slit is that this configuration places the seal in a mechanically receptive position to be easily penetrated by even a flat large diameter luer tip. In addition, this configuration allows the resting concavity at the face to be minimized. If preferred, the upper portion of the septum can be molded in a "mushroom" configuration with the lateral walls thereof sloping downward and the undersurfaces of those lateral walls sloped downwardly, and the septum subsequently slit in this configuration. With this configuration upward deflection of the lateral walls can be induced by lateral portions of the housing that are not elevated and in fact could have a horizontal or even slightly laterally downwardly sloping configuration provided the downward slope is less than the downward slope of the undersurfaces of the lateral walls of the upper portion of the septum. This configuration will induce wedge compression at the slit adjacent the surface of the septum without a significant facial valley.
To provide additional sealing, the septum can have a region of focused compression of a short segment of the slit below and adjacent to the upper portion of the septum and preferably immediately adjacent the portion of the slit sealed by the leverage inducing platforms described supra. A second region of focused compression can be provided adjacent the extension or adjacent a distal end of the septum. The septum can include a lower portion mounted between the opposing platform projections which are aligned with the long transverse axis of the slit and which can project into the corresponding matching grooves in the lateral wall of the septum (which can be the same lateral grooves noted above which separate the upper and lower housing portions). The septum has a lateral transverse dimension intermediate the projections slightly greater than the corresponding internal dimension intermediate the opposing projections between which the septum is positioned. The septum is thereby slightly compressed transversely along a short longitudinal segment of the slit by the opposing projections perpendicular to the slit. This compression can be focused along a short segment of the slit by configuring the projections to have a narrow projecting vertical dimension at the projection ends such as is provided by a relatively pointed end. As described for the upper face, the upper surface of the platform projections are sloped to facilitate vertical deflection or expansion of the septum during insertion of the luer tip. This can also be provided for the lower surface of the projection. This is beneficial because the cylindrical luer lock connector is severely constraining relative to the potential space available for lateral deflection and any vertically deflected volume (especially upward and away from the housing inlet) can reduce the width of the lateral space required. While the focused compression induces resistance to penetration by the luer tip, this resistance can be easily overcome because of the matched shape of the projections and septum allows for expansion around (above and below) the projections into septum expansion receivers such as horizontal slots. A region of reduced resistance to the upwardly wedging force along the septum, such as is provided by extending the opposing lateral slits, intermediate the projections can be provided. The extended lateral slits and the focused compression just below the point wherein the central slit is levered closed allows the upper portion to be wedged upward without pulling open the central slit below the wedge.
When the luer tip is pushed against a septum face with the aforementioned configuration, a facial valley develops, easy penetration occurs, and, upon penetration, the opposing upper portions of the septum lateral to the long transverse axis slit are displaced laterally. To be useful as a luer lock receiver, it is very important to note that despite the receipt of the large diameter luer tip, the extent of lateral expansion of the septum must be contained within a minimal space so that the luer penetration receiver can be threaded into the limited confines of the cylindrical luer lock connector. This is true for both the septum portion contained within the housing and any septum portion above the housing. Also despite the tight space limitations and the need for tight sealing of the slit, lateral expansion of the slit by the luer tip must not be greatly inhibited so as to minimize the force of luer tip penetration into the septum. In the present invention, the housing and the septum are configured to present to each other a reduced vertical cross-sectional surface area for compressive contact between the housing and the septum during lateral septum expansion. This reduces the magnitude of the penetration force required to achieve lateral expansion of the septum thereby minimizing the penetration force. Using narrow opposing platform projections of the inlet wall can minimize this vertical cross-sectional area and facilitate expansion into an associated slot inferior or superior to the projection. By positioning the housing inlet adjacent the upper portion of the septum and by eliminating or reducing any housing structure lateral to the outer wall of the septum upper portion, the functional equivalent of a circumferential slot is achieved for the septum upper portion, allowing ease of lateral displacement of the septum upper portion above the inlet platforms. Alternatively, slots, or cutouts interposed between narrow vertically oriented posts may be used either lateral to the septum upper portion and/or lateral to the septum lower portion. This configuration allows much of the laterally expanded septum mass to be displaced around (above, below, or between) the posts rather than being compressed against it.
As noted previously, the septum further can include an extension having a smaller cross-sectional area than the upper portion projecting centrally within the housing proximal portion to the septum target portion. The slit extends centrally through the septum extension. Providing a slot or a cutout of the lateral wall of the septum extension can provide the smaller cross-sectional area of the extension of the septum. These slots or cutouts can be positioned in parallel alignment with the long transverse axis of the slit between the surrounding housing and the lateral wall of the septum extension. The septum slot or cutout provides room for the expansion of the septum within the confines of the proximal portion of the housing.
In one presently preferred embodiment, the septum further defines an enlarged enhanced sealing region adjacent the distal end of the septum. The slit of this sealing portion is tightly sealed. This may be achieved by a compression seal (of the type disclosed in U.S. Pat. No. 5,466,219). Alternatively, another enhanced sealing configuration may be used. If the compression seal is used, the sealing portion preferably has a greater cross-sectional area lateral to the slit than either the lower portion or the upper portion. The larger area provides room for ease of lateral septum displacement despite compression over a longer length of the slit. Since the enhanced sealing portion may be positioned slightly distal to the maximum intussuseption length of the cylindrical luer lock connector, an improved seal can be provided in this portion by a longer compression seal along the slit since it is not necessary to tightly constrain or minimize the vertical compressive interaction between the housing and septum in the manner discussed supra for the upper, the lower, and the extension portions of the septum. Alternatively, another short focused region of septum compression can be provided along the housing or a septum sealing portion such as a duckbill portion (of the type disclosed in U.S. Pat. No. 5,474,544) may be used.
It is an object and purpose of the present invention to provide an inexpensive, improved luer lock receiving septum having a configuration which provides rapid and tight resealing and yet allows penetration of the septum by the luer tip with a low penetration force.
It is yet a further object of the present invention to provide a deflection inducing member to provide opposing upward deflection of a septum portion to lever closed a slit at the face of the septum.
It is also an object of the present invention to provide a septum face having a minimum effective diameter during luer penetration while providing a maximum diameter of the initial target for luer tip advancement.
Another object the present invention is to provide an elongated septum having a central slit which includes an upper target face of enlarged diameter wherein the septum includes a central lower septum extension projecting about the slit below the inlet and into a housing so that the narrow extension can be more easily penetrated by entry into the narrow extension through the larger face and further so that there is provided sufficient room for both the laterally displaced extension of the septum, the luer taper, and the housing to be received into a conventional luer lock connector.
It is a further object of the present invention to minimize or eliminate the negative pressure deflection normally associated with the withdrawal of the large diameter luer cannula from an enclosed fluid filled lumen by providing isolation from the portion receiving the luer cannula by a distal sealing portion or by providing a septum extension around the slit which functions as a resting fluid displacement member and which inhibits fluid from entering the insertion zone after withdrawal of the luer cannula.
It is further the purpose of the present invention to provide a face, which is comprised of a homogeneous elastomer, which can be comprehensively wiped. (This is similar to the conventional simple reseal used in medicine for decades) The present invention has no open crevices or inaccessible spaces, which have contiguity with the luer, access face, or slit, or fluid path. There is no circumferential piston-to-cylinder space or crevice at the luer contact face of the valve as is associated with the conventional luer access valves in wide use. This space has the greatest potential for colonization. It comprises a circumferential crevice, which is in direct contact with the septum face and it contacts the end of the luer tip and is in direct contiguity with the fluid path. Drops of fluid at the septum outer face will contact both the circumferential crevice and the slit so that contamination contiguity from a microbiologic perspective is operative with the first activation and at any time during subsequent use. Bacteria and fluid gaining entry into the circumferential crevice are displaced back and forth and are not accessible to wiping. Parenteral nutrition fluid gaining entry to the crevice provides a perfect culture medium for rapid bacteria growth. This growth is inaccessible to wiping and is pistoned back and forth in direct contact with fluid droplets on the outer face and the slit itself for potential entry into the patient's blood stream.
It is further the purpose of the present invention to provide a long slit, which provides for a secure seal of the fluid path to reduce the potential for bacterial egress.
It is further the purpose of the present invention to provide a high surface sealing force as by compressive sealing which is applied and focused directly at the surface by the lever action on the upper septum portion. This allows maximum tight sealing exactly at the surface interface with the surrounding environment so tiny open crevices do not form at the surface exit point of the slit. This helps to prevent the egress of droplet contamination at the surface of the slit. This is advantageous over transverse compression alone since a central slit will not lever closed as tightly directly at the surface by transverse compression applied below the upper surface of the septum. Indeed if the surface is induced into a convex configuration by transverse compression then there can be a tendency for slight gapping of the slit at the surface.
It is further the purpose of the present invention to provide a septum with relatively high mass so that the slit is more securely and more robustly sealed in a range of usage situations.
It is further the purpose of the present invention to provide a simple configuration having only a septum and outer housing, and wherein there are no internal parts in contiguity with the fluid path.
It is further the purpose of the present invention to provide a wiping action of the long septum on the luer tip, which wiping action can be exploited further by adding an antimicrobial agent to the elastomer as discussed below.
It is further the purpose of the present invention to provide a design wherein the entire contact between the luer tip and the valve is with the elastomer.
It is further the purpose of the present invention to provide an antimicrobial barrier associated with the elastomer such an antimicrobial coating of the elastomer (as is known in the art) or as by molding the septum from an antimicrobial elastomer (such antimicrobial elastomers are known in the art). This assures that a comprehensive barrier is provided at all surfaces potentially contacting the luer tip during insertion. Since the luer tip contacts only the elastomer during and after insertion, there is no need to coat or otherwise apply antimicrobial to or within the housing structure although it may be applied if desired.
It is further the purpose of the present invention to provide a distal seal in combination with a long slit which therefore allows a syringe attached to a luer tip extending through the septum to be decompressed upon partial withdrawal within the septum to avoid blood spurting during blood sampling. (The background of the prevention of blood spurting during pressurized blood sampling can be reviewed in U.S. Pat. No. 5,114,400, the disclosure of which is incorporated by reference as if completely disclosed herein).